Sen. Rand Paul (R-KY) has taken President Trump's side in his war of words with Mitt Romney. Romney started it by publishing an op-ed Tuesday night accusing the president of ruining U.S. relationships with several of our friends on the world stage, as well as disgracing the office of presidency.

Paul suggested Romney was the one with the behavior issues. The senator-elect from Utah is “virtue signaling” and “puffing himself up that he’s somehow so virtuous,” Paul said when give a chance to sound off on Fox News's Neil Cavuto Wednesday.

Paul added that it's a "low blow" for Romney to attack Trump's character and calling the president dishonest "is not productive and I think it's going to backfire on him."

Cavuto was quick to note that Sen. Paul had his own share of insults for Trump when the two were competing in the Republican primary in 2015. In fact, he said "worse things" about his opponent than Romney did. For instance, Paul sounded off on Trump's "visceral attacks" on people's appearances and said Trump had a "sophomoric quality" about him.

Paul didn't deny it.

"The tenor is different when you're competing for the same office and the same election," Paul noted. "I had some choice words."

But, as soon as Trump stepped foot in the Oval Office, Paul cooled it with the character assassinations. Sure he has disagreements with the president and votes against him from time to time, but personal attacks are out of bounds.

“Since he’s been elected president, I try not to have personal character assassination or attacks on him and I try to work with him.”

Trump spent several minutes of his own responding to Romney's op-ed after a meeting with his cabinet Wednesday. He said he was "surprised" that Romney had rebuked him "this quickly," particularly because he seemed "happy" when he endorsed him in his Utah Senate race. The president also mused aloud that had Romney fought against Barack Obama in the 2012 presidential election as hard as he's fighting against him, "he would've won."